If you were told that by 2036 the number of councils in Sydney with populations of more than 200,000 would be seven times the number today, you might be forgiven for thinking that these forecasts were based on some fairly strong assumptions about council amalgamations.

In fact, as somebody pointed out to me recently, if Sydney’s population grows in the way that State Government forecasts suggest, the mega-councils, or at least the reasonably large councils, will come to us without a single boundary change or amalgamation.

A check of the latest forecasts from the NSW Transport Data Centre (TDC – in the process of becoming the Bureau of Transport Statistics) makes this clear. These assume that the population of the Sydney Greater Metropolitan Area (GMA, which also includes the Hunter and Illawarra) will grow by almost two million people, from 5.21 million to 7.19 million, an increase of around 40%. The TDC has also made forecasts of Local Government Area (LGA) population growth based on the current council boundaries.

Before I go on I should make all the usual qualifications – population forecasting this far out, especially at the LGA level, is an inexact science, reliant on all sorts of assumptions about factors such as migration and decentralisation policies. Lately some of these factors have come under intense scrutiny as part of the “Big Australia” debate.

These forecasts are also based on another fundamental presumption – that the current council boundaries will not change at all in the next 25 years. However, it is instructive to run with this and see what happens if the current boundaries are left intact.

First, a 40% increase in Sydney’s population would mean a similar substantial increase in average council size, from 98,300 to 135,600. Naturally this growth rate will not be uniform across all councils but even if it is, the outcomes in numerical terms are obviously going to be much more noticeable in the larger councils.

The graph below shows the distribution of councils in 2006 and 2036 in population bands starting with zero to 50,000, 50,000 to 100,000 and so on. Councils with over 200,000 have been grouped together in a single band. The number at the bottom of each column is the number of councils in that band for either 2006 or 2036.

Sydney Councils: projected growth by population bands, 2006-2036

It should be noted a similar number of councils in 2006 and in 2036 in a particular band does not necessarily mean that these are the same councils. Some 2006 councils may have increased in population to the extent that they have moved into a higher band, to be replaced by councils increasing in population from the band below.

With that qualification in mind, let’s have a look at the estimates. The middle bands, 50,000 to 100,000 and 100,000 to 150,000, remain relatively stable both in terms of the number of councils and population. However the number of councils under 50,000 is halved from 12 to 6, while the number of councils in the 150,000 to 200,000 band decreases from 11 to 6. Both bands will also experience similar proportional declines in total population.

The story for the 200,000 councils is a marked contrast. In 2006 there were only two (Blacktown and Sutherland), totalling just under half a million. By 2036 there could be 14 such councils with a combined population of over 3.6 million.

It can be argued that most of the projected 12 additional members of the “200,000 club” were in the 150,000 to 200,000 category in 2006 and that this change is merely one of degree. To an extent this is true, but there are a few interesting exceptions. Campbelltown and Wyong leapfrog from the 100,000 to 150,000 band into this group, but the most spectacular change is that projected for Camden, which is estimated to grow from under 51,000 to nearly 250,000 in this period as a result of the development projected for Sydney’s south-west.

It also has to be acknowledged that the forecast overall increase in the proportion of Sydney’s population in the largest councils, at around 2%, is relatively incremental. However if the overall population projections prove to be accurate and council boundaries remain unchanged, there could be some interesting challenges and opportunities in having 14 councils of this size collectively responsible for providing local services and infrastructure to over half of Sydney’s population by 2036.